1. Field of the Invention
The present invention relates in general to seat slide devices for use in a motor vehicle, and more particularly, to seat slide devices of a power type. More specifically, the present invention is concerned with a power seat slide device which comprises generally stationary rails secured a vehicle floor, movable rails slidably engaged with the stationary rails and carrying thereon a seat, and an electric power unit for driving the movable rails relative to the stationary rails.
2. Description of the Prior Art
In order to clarify the task of the present invention, one conventional power seat slide device will be outlined with reference to FIGS. 5 and 6 of the accompanying drawings, which is disclosed in Japanese Patent First Provisional Publication No. 64-60445.
The power seat slide device of the publication comprises paired (that is, right and left) rail units 1A and 1B which are illustrated in FIGS. 5 and 6 respectively.
As shown, each rail unit 1A or 1B comprises a stationary rail 3 secured to a vehicle floor (not shown) and a movable rail 2 slidably engaged with the stationary rail 3 carrying on a seat (not shown). For achieving the sliding movement of the movable rail 2 relative to the stationary rail 3, the movable rail 2 has at its sides respective downward guide walls 2a by and in which parts 3a of the stationary rail 3 are slidably received. For smoothing the sliding movement of the movable rail 2, a plastic slider 4 is intimately interposed between each guide wall 2a and the corresponding part 3a of the stationary rail 3.
However, due to the inherent construction, this conventional power seat slide device has the following drawbacks.
Since assured and smoothed movement of the movable rails 2 relative to the stationary rails 3 depends greatly on the dimensional condition of the plastic sliders 4, production of such plastic sliders 4 requires a highly skilled molding technique. This increases production cost of the power seat slide device. In fact, if the plastic sliders 4 have poor dimensional condition, undesired play of the movable rails 2 tends to occur during the movement thereof.